Fiducial Markers for Analyzing Human Jaws

ABSTRACT

Example fiducial markers include features that make them particularly useful in dental scanning methods for analyzing jaws of a patient, wherein the dental scanning methods involve taking multiple scans of the jaws, and/or models thereof, and then shifting the image of one scan to match that of another. Prior to scanning, the fiducial markers are attached to the patient&#39;s jaws to accurately identify and track the relative position of the jaws.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending patentapplication Ser. No. 16/783,678 filed on Feb. 6, 2020 and claims thebenefit of provisional patent application Ser. No. 62/978,778 filed onFeb. 19, 2020.

FIELD OF THE DISCLOSURE

This patent generally pertains to dentistry and more specifically tofiducial markers attachable to human jaws to assist a dentalpractitioner in comparing multiple radiographic scans of the jaws andattached markers to analyze bite registration and other jaw-relatedfeatures.

BACKGROUND

A typical jaw of a person or human patient includes a maxilla (upperjaw) and a mandible (lower jaw). Temporamandibular joints (TMJ) allowpivotal and some translational relative movement between the maxilla andmandible, so the person can pivotally open and close their mouth. Boththe maxilla and mandible comprise an alveolar bone for supporting teeth.A curved portion of the alveolar bone is known as the alveolar arch,which curves about an oral cavity within the person's mouth. The oralcavity is the space that contains the person's tongue.

Normally, when a person closes their mouth, the teeth in the upper andlower jaws come together in a comfortable engaging relationship known asproper bite registration. Other times, however, malpositioned teeth,missing teeth or interfering dental appliances prevent the jaws fromclosing in proper bite registration. This can create a number ofproblems such as stressing the temporamandibular joints, concentratinglocalized force on certain teeth, and creating a poor visual appearance.Consequently, various dental treatments are used for correcting suchproblems.

Planning and performing certain dental treatments might first involvecreating physical cast models of a patient's upper and lower jaws andanalyzing how well the cast models fit together before and aftertreatment. Some example treatments include installing dentures,repairing dentures, installing implants, applying crowns, jaw surgery,applying braces, and removing teeth.

In some cases, various scanners are used for assisting in the dentaltreatment process. Some scanners generate a dicom file, which is anacronym for Digital Imaging and Communications in Medicine. Some dicomfiles have a .dcm file extension.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of an example patient that has no upper teeth andis missing one lower tooth.

FIG. 2 is a front view of the patient shown in FIG. 1 but with theaddition of a poor-fitting upper denture.

FIG. 3 is a front view of the patient shown in FIG. 1 but with theaddition of a new upper denture and an implant replacing the missinglower tooth.

FIG. 4 is a front view of the patient's upper and lower jaws withfiducial markers being installed in the upper jaw, just above thepoor-fitting upper denture.

FIG. 5 is a front view similar to FIG. 4 but showing the fiducialmarkers already installed.

FIG. 6 is a front view similar to FIG. 4 but showing fiducial markersbeing installed in both the upper and lower jaws.

FIG. 7 is a front view similar to FIG. 6 but showing the fiducialmarkers already installed.

FIG. 8 is a set of orthogonal views showing an example scanningarrangement of fiducial markers screwed into in a schematicallyillustrated alveolar bone of either an upper or lower jaw.

FIG. 9 is a set of orthogonal views showing another example scanningarrangement of fiducial markers screwed into in a schematicallyillustrated alveolar bone of either an upper or lower jaw.

FIG. 10 is a schematic diagram illustrating various method stepsassociated with a first scanning machine.

FIG. 11 is a front view showing example dental appliances being addedand removed from the patient as shown in FIG. 2.

FIG. 12 is a front view showing an example method for creating castmodels of the patient's jaws after the addition or removal of exampledental appliances.

FIG. 13 is a front view of cast models created by the method shown inFIG. 12.

FIG. 14 is a schematic diagram showing additional example scanningmethods.

FIG. 15 is front view of a computer displaying multiple scan results ofjaws and a schematic depiction of a dental practitioner mouse-clinkingon certain points of the scan results.

FIG. 16 is front view similar to FIG. 15 but showing a schematicdepiction of the dental practitioner mouse-clinking on other points ofthe scan results.

FIG. 17 is front view similar to FIG. 15 but showing a schematicdepiction of the dental practitioner mouse-clinking on additional pointsof the scan results.

FIG. 18 is front view similar to FIG. 15 but showing a schematicdepiction of the dental practitioner mouse-clinking on even more pointsof the scan results.

FIG. 19 is a front view similar to FIGS. 15-18 showing upper and lowerjaws on the right side of the computer display being shifted to create adigital jaw model having a bite registration that matches that of theupper and lower jaws on the left side.

FIG. 20 is a front view similar to FIG. 19 but showing the upper andlower jaws on the right side having been shifted so as to coincide withthe positional relationship of the upper and lower jaws on the leftside, whereby the jaws on both sides of the display have substantiallythe same bite registration.

FIG. 21 is a front view of example jaw images that include some exampleconstellations of points.

FIG. 22 is a front view similar to FIG. 21 but with some of theconstellations of points shifted to another position.

FIG. 23 is a front view of the computer displaying the recently createddigital jaw model with virtual teeth and virtual dentures being fittedto the digital jaw model.

FIG. 24 is a front view similar to FIG. 23 but with the virtual dentalappliances fitted in position.

FIG. 25 is a side view of an example fiducial marker constructed inaccordance with the teachings disclosed herein.

FIG. 26 are side views of another example fiducial marker constructed inaccordance with the teachings disclosed herein.

FIG. 27 are side views of yet another example fiducial markerconstructed in accordance with the teachings disclosed herein.

FIG. 28 is an enlarged view of area 25 identified in FIG. 16 and asviewed along a Z-axis (FIG. 36).

FIG. 29 is an enlarged view similar to FIG. 28 but as viewed fromanother perspective, i.e., as viewed along an X-axis (FIG. 36)

FIG. 30 is a view similar to FIG. 28 but further showing the assignmentof a geometric feature.

FIG. 31 is a view similar to FIG. 29 but further showing the assignmentof the geometric feature.

FIG. 32 is a view similar to FIGS. 28 and 30 but further showing thegeometric feature being moved into alignment with a marker body.

FIG. 33 is a view similar to FIGS. 29 and 31 but further showing thegeometric feature being moved into alignment with the marker body.

FIG. 34 is a view similar to FIG. 32 but showing the geometric featurealigned with the marker body.

FIG. 35 is a view similar to FIG. 33 but showing the geometric featurealigned with the marker body.

FIG. 36 is a front view similar to FIG. 15 but showing one of the scanresults being adjusted in various dimensions.

FIG. 37 is a flow chart illustrating example steps in digital imageanalytics for iteratively adjusting a digital image.

FIGS. 38-43 are schematic diagrams illustrating various method steps foranalyzing jaws of a patient.

FIG. 44 is a side view of an example fiducial marker constructed inaccordance with the teachings disclosed herein.

FIG. 45 is an exploded side view illustrating the interchangeability atool and a marker body with a screw.

FIG. 46 is a cross-sectional view taken along line 46-46 of FIG. 45.

FIG. 47 is a side view similar to FIG. 45 but showing the tool attachedto the screw.

FIG. 48 is a side view similar to FIG. 45 but showing the marker bodyattached to the screw.

FIG. 49 is a side view of another example fiducial marker.

FIG. 50 is a right end view of FIG. 49

FIG. 51 is a side view of an example analog with a protruding pin.

FIG. 52 is a side view of the analog shown in FIG. 51 but with its pinremoved.

FIG. 53 is a top view of FIG. 54

FIG. 54 is a front view of an example holder.

FIG. 55 is a right side view of FIG. 54.

FIG. 56 is a right side view similar to FIG. 55 but with the examplefiducial marker of FIG. 49 inserted in the holder.

FIG. 57 is a right side view similar to FIG. 55 but with the exampleanalog of FIG. 52 inserted in the holder.

FIGS. 58-63 are schematic diagrams illustrating other various methodsteps for analyzing jaws of a patient, wherein FIGS. 58-63 correspond toFIGS. 38-43, respectively.

FIGS. 64-69 are schematic diagrams illustrating still other variousmethod steps for analyzing jaws of a patient, wherein FIGS. 58-63 alsocorrespond to FIGS. 38-43, respectively.

FIG. 70 is a side view similar to FIG. 45 but showing another examplescrew constructed in accordance with the teachings disclosed herein.

FIG. 71 is a right end view of FIG. 70.

FIG. 72 is a left end view of FIG. 73.

FIG. 73 is a side view similar to FIG. 45 but showing another examplemarker body and extension constructed in accordance with the teachingsdisclosed herein.

FIG. 74 is a cross-sectional view taken along line 74-74 of FIG. 73.

FIG. 75 is a side view similar to FIG. 48 but showing the example screwand marker body of FIGS. 70-74.

FIG. 76 is a side view similar to FIG. 47 but showing the example screwof FIGS. 70 and 71 and the example tool of FIGS. 45 and 47.

DETAILED DESCRIPTION

FIGS. 1-27 pertain to a dental scanning method for analyzing jaws of apatient 10 by taking multiple scans of the jaws, and/or models thereof,and then shifting the image of one scan to match that of another. Insome examples, fiducial markers are attached to the patient's jawsbeforehand to accurately identify and track the relative position of thejaws. The method provides a way for creating a precise image of an upperjaw 12 a and a lower jaw 12 b in their proper bite registration, eventhough the resulting image may show an insufficient number of teeth toreadily do so. The final, properly shifted image serves as a virtual 3Djaw that can be manipulated and analyzed to aid in various orthodonticand other dental treatments.

The method can be applied to an infinite variety of patients andtreatments. Some example treatments include installing dentures,repairing dentures, installing implants, applying crowns, jaw surgery,grinding teeth, shifting teeth, removing teeth, and all otherconceivable modifications to the craniofacial complex. For sake ofexample, the present method can be applied to patient 10, shown in FIGS.1-3. In this particular example, patient 10 has no upper teeth and ismissing a lower tooth, as shown in FIG. 1. Prior to using the methoddisclosed herein, patient 10 wore an old, poor fitting upper denture 14and left an area 16 of the missing lower tooth open, as shown in FIG. 2.

Following treatment, patient 10 is provided with a well fitting upperdenture 18 plus an implant 20 to fill the space of the missing tooth, asshown in FIG. 3. The term, “implant” refers to an anchor 22 attached toa jaw bone and/or a crown 24 attached to anchor 22. Some exampleimplants further include a post 26 (e.g., a screw, a rod, a pin, etc.)for fastening crown 24 to anchor 22.

Patient 10 has two jaw members 12 including upper jaw 12 a (maxilla) andlower jaw 12 b (mandible). The term, “first jaw” refers to either jaw,the maxilla or the mandible. Likewise, the term, “second jaw” refersinterchangeably to the maxilla or mandible. FIGS. 4-7, 11 and 12 showthe patient's actual jaw members 12, not models thereof. FIGS. 4-7 showjaws 12 a and 12 b in the condition similar to that shown in FIG. 2,wherein old denture 14 is on upper jaw 12 a and space 16 is left empty.

To provide jaw 12 a and/or jaw 12 b with reference points that helpidentify the jaws' relative location and orientation in later scannedimages of jaws 12 a and 12 b, some example methods involve installingmultiple fiducial markers 28 into an alveolar bone 30 (FIGS. 8 and 9) ofjaw 12 a and/or 12 b. The term, “alveolar bone” refers to the bonystructure of either jaw 12 a or 12 b. The term, “fiducial marker” refersto any item that includes a substantially radiopaque feature.

Some examples of fiducial marker 28 comprise a shaft 32 extending alonga longitudinal axis 34 from a marker body 36. The term, “shaft” refersto any elongate member that is generally cylindrical, tapered and/orthreaded. Some examples of shaft 32 include a screw, a straight pin, atapered pin, a rod, a nail, etc. In the illustrated examples, shaft 32is a screw 38. The term, “marker body” refers to any structure of anyshape that is substantially radiopaque. In some examples, marker body 36is generally spherical and made of a polymer with 10% barium sulfate. Insome examples, marker body 36 is overmolded or otherwise attached to ahead 40 of screw 38. Some examples of screw 38 are made of a generallynoncorrosive material, such as stainless steel, carbide or titanium.Head 40, in some examples, has a tool-mating geometry, so screw 38 canbe readily driven into jaw member 12. Various examples of fiducialmarker 28 are shown in FIGS. 25-27 and will be described later in moredetail.

For minimal invasiveness, in some examples, markers 28 are onlyinstalled in one of jaw members 12, as shown in FIGS. 4 and 5, anddistinct stable features 42 of teeth 44 are used as reference points onthe other jaw member 12. Some examples of features 42 include chosenedges, corners, faces, and peaks of individual teeth 44 or a dentalappliance supported by one of the jaws 12. More specific examplesinclude a first feature 42 a (face of a first chosen tooth), a secondfeature 42 b (face of a second chosen tooth), and a third feature 42 c(face of a third chosen tooth).

In the example shown in FIGS. 4 and 5, fiducial markers 28 include aright fiducial marker 28 a, a left fiducial marker 28 b, and a frontfiducial marker 28 c. Arrows 46, 48 and 50 respectively representattaching right fiducial marker 28 a to a right portion 52 of first jaw12 a, attaching left fiducial marker 28 b to a left portion 54 of firstjaw 12 a, and attaching front fiducial marker 28 c to a front portion 56of first jaw 12 a. FIG. 5 shows markers 28 a, 28 b and 28 c in theirinstalled positions. Such a spread-out arrangement of three markers 28provides upper jaw 12 a with a broad footprint for maximum positionalaccuracy.

In addition or alternatively, FIGS. 6 and 7 show the installation of asecond set 58 of three fiducial markers 28 comprising a right fiducialmarker 28 d, a left fiducial marker 28 e, and a front fiducial marker 28f Arrows 60, 62 and 64 respectively represent attaching left fiducialmarker 28 d to a right portion 66 of second jaw 12 b, attaching leftfiducial marker 28 e to a left portion 68 of second jaw 12 b, andattaching front fiducial marker 28 f to a front portion 70 of second jaw12 b. FIG. 6 shows markers 28 d, 28 e and 28 f in their installedpositions.

In some examples, the second set 58 of fiducial markers 28 provides amore precise indication of the second jaw's location and orientationthan what is otherwise achieved by relying instead on distinct features42 of teeth 44. This is because markers 28 d, 28 e, and 28 f can be morespread out than teeth 44, and the size of marker bodies 36 is usuallysmaller than teeth 44.

FIGS. 8 and 9 are sets of orthogonal views showing example scanningarrangements 72 of fiducial markers 28 screwed into in a schematicallyillustrated alveolar bone 30 of either jaw member 12. FIG. 8 shows afront view 74, a top view 76, and a right side view 78 of jaw member 12with fiducial markers 28 in an ideal arrangement. FIG. 9 shows the sameviews 74, 76 and 78 but with fiducial markers 28 in a more misalignedyet still acceptable configuration. From a vertical perspective, asshown in top view 76 of FIGS. 8 and 9, fiducial markers 28 extend beyondthe general outer perimeter of jaw member 12 (i.e., outer perimeter inthe vicinity of markers 28). Fiducial markers 28 thus provide a broaderfootprint for greater positional accuracy, as mentioned earlier.

FIGS. 8 and 9 show fiducial markers 28 and alveolar bone 30 in relationto an oral cavity 80 of patient 10. Oral cavity 80 is the areasurrounded by alveolar bone 30. In the illustrated examples, screw 38 ofeach of the three fiducial markers 28 points inward toward a centralregion 82 of oral cavity 80 when fiducial markers 28 are attached toalveolar bone 30.

In some examples, for maxilla 12 a, fiducial marker 28 c is installedjust below the midline of the anterior nasal spine, at the end of thesuperior labial frenulum. In some examples, fiducial markers 28 a and 28b are installed just anterior of the maxillary tuberosity, with marker28 a on the right side and marker 28 b on the left side.

In some examples, for mandible 12 b, fiducial marker 28 f is installedin the medial border of the hemi-mandible, near the alveolar crest. Insome examples, fiducial markers 28 d and 28 e are installed along theoblique line, just below the posterior-most teeth, with marker 28 d onthe right side and marker 28 e on the left side.

It has been discovered that the arrangements shown in FIGS. 8 and 9provide good results when each fiducial marker's angular deviation(angle 84) is within 45 degrees of a predetermined ideal layout. Morespecifically, in the illustrated examples, each marker body 28 defines acenter point 86 and are arranged such that:

a) center points 86 of fiducial markers 28 a, 28 b and 28 c define aplane 88 (in some examples, plane 88 is generally parallel to anocclusal plane 90 of patient 10);

-   -   b) center point 86 of left fiducial marker 28 b and center point        86 of right fiducial marker 28 a define a lateral line 92        intersecting center point 86 of left fiducial marker 28 b and        center point 86 of right fiducial marker 28 a;    -   c) center point 86 of front fiducial marker 28 c defines a        forward line 94 intersecting center point 86 of front fiducial        marker 28 c, intersecting lateral line 92, and being        perpendicular to lateral line 92;    -   d) shaft 32 of left fiducial marker 28 b lies within an angle 84        of 45 degrees of lateral line 92 as viewed from a direction        perpendicular to plane 88;    -   e) shaft 32 of left fiducial marker 28 b lies within an angle 84        of 45 degrees of lateral line 92 as viewed from a direction        parallel to plane 88 and perpendicular to lateral line 92;    -   f) shaft 32 of right fiducial marker 28 a lies within an angle        84 of 45 degrees of lateral line 92;    -   g) shaft 32 of right fiducial marker 28 a lies within an angle        84 of 45 degrees of lateral line 92 as viewed from a direction        parallel to plane 88 and perpendicular to lateral line 92;    -   h) shaft 32 of front fiducial marker 28 c lies within an angle        84 of 45 degrees of forward line 94; and    -   i) shaft 32 of front fiducial marker 28 c lies within an angle        84 of 45 degrees of lateral line 92 as viewed from a direction        parallel to plane 88 and perpendicular to lateral line 92.

In the example shown in FIGS. 4, 5 and 10, three fiducial markers 28 a,28 b and 28 c in upper jaw 12 a and three features 42 a, 42 b and 42 cof lower jaw 12 b will be used as clear, distinct reference points formarking the location of upper jaw 12 a relative to lower jaw 12 b.Further steps in some examples of the present dental scanning methodwill now be explained with reference to FIGS. 10-24.

FIG. 10 illustrates creating 96 a first scan result 98 by scanning 100first jaw 12 a, second jaw 12 b; three fiducial markers 28 a, 28 b and28 c on first jaw 12 a; and three features 42 a, 42 b and 42 c on secondjaw 12 b. In some examples, first scan result 98 is created by scanning100 fiducial markers 28 d, 28 e and 28 f in addition or alternatively tocapturing features 42 a, 42 b and 42 c.

In either case, scanning 100 is done while jaws 12 are in apredetermined target bite position relative to each other. In someexamples, the predetermined target bite position is referred to as aproper bite registration, wherein the teeth and/or other installeddental appliances fit comfortably together in a generally closedposition without subjecting the temporamandibular joints to undo stress.An example of such a predetermined target bite position, or proper biteregistration, is shown in FIG. 2 and the upper left corner of FIG. 10.

The term, “dental appliance” refers to any device temporarily orpermanently installed within a patient's mouth. Some example dentalappliances include full dentures, partial dentures, bridges, crowns,cavity fillings, braces, implants, etc. In some examples, dentalappliances and a patient's actual teeth are some examples of “spacers,”as both teeth and dental appliances limit how closely upper jaw 12 a andlower jaw 12 b can come together.

Scanning 100, as shown in FIG. 10, can be done by any suitable scanningmethod. Some example methods of scanning 100 include cone beam computedtomography (CBCT), magnetic resonance imaging (MRI), computed tomography(CT or CAT), X-ray, etc. In some examples, scanning 100 is performedusing a CBCT scanning machine 102 (first scanning machine 102). Someexamples of first scanning machine 102 include an i-Cat FLX.I cone beam3D imaging scanner manufactured by Imaging Sciences International LLC ofAlpharetta, Ga. or Hatfield, Pa.

From first scanning machine 102, first scan result 98 is transferred ina file format 104 to a computer 106, as indicated by arrows 108 of FIG.10. In some examples, first scanning machine 102 generates first scanresult 98 in a first format (e.g., a dicom file), and computer 106converts the first format to a more manageable digital format (e.g., anstl file). In some examples, the file conversion is accomplished throughdental treatment planning software executed by computer 106. Someexamples of such software include exocad, 3shape, dental wings, andDentsply Sirona. In other examples, first scanning machine 102 generatesfirst scan result 98 directly in a more manageable digital formatwithout the need for subsequent file conversion by computer 106.

FIG. 10 also shows computer 106 displaying first scan result 98including a first scanned representation of the first jaw 110, a firstscanned representation of the second jaw 112, and a first constellationof points 114. In some examples, first constellation of points 114represents three fiducial markers 28 a, 28 b and 28 c; as shown in theleft-bottom of FIG. 10. In some examples, first constellation of points114 represents three fiducial markers 28 a, 28 b and 28 c on first jaw12 a plus three features 42 a, 42 b and 42 c on second jaw 12 b; alsoshown in the left-bottom of FIG. 10. In some examples, firstconstellation of points 114 represents three fiducial markers 28 a, 28 band 28 c on first jaw 12 a plus second set 58 of three fiducial markers28 d, 28 e and 28 f on second jaw 12 b; shown in the right-bottom ofFIG. 10.

First scan result 98, regardless of which example of first constellationof points 114 is being used, provides a reference against whichsubsequent scans will be compared. Such later scans will be used forcreating an accurate digital jaw model 116 (FIGS. 20, 23 and 24) thatcan be manipulated and analyzed in the treatment of patient 10. Variousmethod steps for producing such scans are shown in FIGS. 11-14.

Arrow 118 of FIG. 11 represents old dentures 14 being removed from thepatient's upper jaw 12 a. Since dentures 14 limit how closely jaws 12can close, dentures 14 are considered as being a spacer 120, and arrow118 represents removing spacer 120 from patient 10. In this example,arrows 122 represent attaching implant 20 (e.g., anchor 22 and post 26)to lower jaw 12 b, thus arrows 122 more broadly represent attachingimplant 20 to at least one of first jaw 12 a and second jaw 12 b anddoing so after creating first scan result 98 (FIG. 10) but beforecreating at least one of a second scan result 124 (FIG. 14) and a thirdscan result 126 (FIG. 14). FIG. 10, on the other hand, shows jaws 12being scanned while spacer 120 (e.g., old dentures 14) are still inplace to help position jaws 12 at the predetermined target bite positionfor proper bite registration.

FIG. 12 illustrates a conventional method of using a known moldingmaterial 128 for creating molds 130 and 132 of jaws 12 a and 12 b,respectively. In this example, molds 130 and 132 capture the contours ofjaws 12 a and 12 b including the shapes of implant 20; markers 28 a, 28b and 28 c; features 42 a, 42 b and 42 c; the void due to the omissionof dentures 14; and markers 28 d, 28 e and 28 f (if used). Molds 130 and132, however, can be independent of each other, so they do notnecessarily capture the relative positions of jaws 12 a and 12 b.

Molds 130 and 132 produce a physical model 134 of first jaw 12 a and aphysical model 136 of second jaw 12 b, as shown in FIG. 13. In someexamples, models 134 and 136 are castings created within the moldcavities of molds 130 and 132. Such methods of creating physical models134 and 136 are well known to provide accurate reproductions of thesurface geometries of jaws 12.

FIG. 14 illustrates creating second scan result 124 by scanning 138first jaw 12 a directly via a scanner 140 or scanning 142 the physicalmodel 134 of first jaw 12 a via a scanner 144. FIG. 14 also illustratescreating third scan result 126 by scanning 146 second jaw 12 b directlyvia scanner 140 or scanning 148 the physical model 136 of second jaw 12b via scanner 144. Some examples of scanner 140 include a CarestreamCS3600 intraoral scanner provided by Carestream Dental LLC of Rochester,N.Y. or Atlanta, Ga. Some examples of scanner 144 include a MeditIdentica T500 benchtop scanner of Seoul, South Korea.

In some examples, using scanner 144 for scanning models 134 and 136provides a sharper, more distinct image of individual jaws 12 a and 12 bthan what can be achieved with scanner 102 (FIG. 10). Scanner 102,however, provides a clear representation of the jaws' relative positionin their natural bite registration. So, there is a benefit to using bothscanners 102 and 144, wherein scanner 102 is an example of a firstscanning machine, scanner 144 is an example of a second scanningmachine, and scanners 102 and 144 are two different scanning machines.

Using intraoral scanner 140 for scanning jaws 12 directly is analternative to using scanner 144. Scanner 140 eliminates the need forcreating models 134 and 136; however, scanner 140 might accumulate aseries of incremental positional errors while traversing a significantdistance across jaws 12. Both scanners 140 and 144 are considered“second scanning machines” and each one is different than first scanningmachine 102.

Regardless of which second scanning machine 140 or 144 is used, scanners140 and 144 generate second scan result 124 representing upper jaw 12 aand third scan result 126 representing lower jaw 12 b. Arrow 150represents transmitting second scan result 124 of upper jaw model 134from scanner 144 to computer 106, arrow 152 represents transmittingthird scan result 126 of lower jaw model 136 from scanner 144 tocomputer 106, arrow 154 represents transmitting second scan result 124of upper jaw 12 a to computer 106, and arrow 156 represents transmittingthird scan result 126 of lower jaw 12 b to computer 106.

In response to receiving scan information from scanner 140 or 144,computer 106 displays second scan result 124 and third scan result 126,as shown in FIG. 14. Second scan result 124 includes a second scannedrepresentation of the first jaw 158 and a second constellation of points162 representing the three fiducial markers 28 a, 28 b and 28 c. Thirdscan result 126 includes a second scanned representation of the secondjaw 160. In some examples, third scan result 126 further includes athird constellation of points 164 representing features 42 a, 42 b and42 c and/or representing the second set of fiducial markers 28 d, 28 eand 28 f.

In some examples, the first constellation of points 114, the secondconstellation of points 162, and/or the third constellation of points164 are used as reference points in shifting the individual jaw imagesin the second scan to match the properly fitting jaw image in the firstscan. In other words, shifting second scanned representation of thefirst jaw 158 (e.g., upper jaw 12 a) relative to second scannedrepresentation of the second jaw 160 (e.g., lower jaw 12 b) so theyalign with first scanned representation of the first jaw 119 (e.g.,upper jaw 12 a) and first scanned representation of the second jaw 112(e.g., lower jaw 12 b). The goal is to shift the sharp, clear individualjaw images of jaws 12 a and 12 b in the second scan (FIG. 14) accordingto the bite registration of the first scan (FIG. 10) to create theprecise digital jaw model 116 (FIGS. 20, 23 and 24) that can bemanipulated and analyzed to aid in various orthodontic and other dentaltreatments.

FIGS. 15-20 illustrate an example of creating digital jaw model 116(FIG. 20) by shifting (arrows 166 of FIG. 19) the second scannedrepresentation of the first jaw 158 relative to second scannedrepresentation of the second jaw 160 such that the second constellationof points 162 relative to the second scanned representation of thesecond jaw 160 substantially coincides with the first constellation ofpoints 114 relative to the first scanned representation of the secondjaw 112.

In some examples, creating an association of fiducial markers 28 and/orfeatures 42 in the second and third scan results 124 and 126 and thecorresponding fiducial markers 28 and/or features 42 in the first scanresult 98, involves a dental practitioner 168 (e.g., a dentist, a labtechnician, etc.) manually identifying via mouse-clicking 170 on selectpairs of points of constellations 114, 162 and 164 for whichassociations are to be established. Constellations 114, 162 and 164 eachcomprise a plurality of individual points 172. Mouse-clicking 170 is oneexample method for manually identifying where the plurality ofindividual points 172 are located in space (e.g., identifying theircoordinates) and for determining how far at least some of the pluralityof individual points 172 should be shifted.

In some examples, referring to FIG. 21, first constellation of points114 includes points 114 a, 114 b and 114 c, which correspond to fiducialmarkers 28 a, 28 b and 28 c, respectively. In addition or alternatively,some examples of first constellation of points 114 includes points 114d, 114 e and 114 f, which correspond to features 42 a, 42 b and 42 c,respectively. In addition or alternatively, some examples of firstconstellation of points 114 includes points 114 g, 114 h and 114 i,which correspond to fiducial markers 28 d, 28 e and 28 f, respectively.

In some examples, second constellation of points 162 includes points 162a, 162 b and 162 c, which correspond to fiducial markers 28 a, 28 b and28 c, respectively.

In some examples of third constellation of points 164 includes points164 a, 164 b and 164 c, which correspond to features 42 a, 42 b and 42c, respectively. In addition or alternatively, some examples of thirdconstellation of points 164 includes points 164 d, 164 e and 164 f,which correspond to fiducial markers 28 d, 28 e and 28 f, respectively.

In some examples, a composite constellation of points 174 comprises acombination of the second and third constellation of points 162 and 164.Some examples of the composite constellation of points 174 includepoints 162 a, 162 b and 162 c plus points 164 a, 164 b and 164 c. Someexamples of the composite constellation of points 174 include points 162a, 162 b and 162 c plus points 164 d, 164 e and 164 f.

FIG. 15 illustrates mouse-clicking 170 on point 114 c of firstconstellation of points 114 and mouse-clicking 170 on point 162 c ofsecond constellation of points 162. In response to such mouse-clicking,computer 106 determines that points 114 c and 162 c represent the samepoint (marker 28 c) on first jaw 12 a.

FIG. 16 illustrates mouse-clicking 170 on point 114 b of firstconstellation of points 114 and mouse-clicking 170 on point 162 b ofsecond constellation of points 162. In response to such mouse-clicking,computer 106 determines that points 114 b and 162 b represent the samepoint (marker 28 b) on first jaw 12 a.

Likewise, similar mouse-clicking on point 114 a of first constellationof points 114 and mouse-clicking 170 on point 162 a of secondconstellation of points 162 is interpreted as meaning that points 114 aand 162 a represent the same point (marker 28 a) on first jaw 12 a.

FIGS. 17 and 18 show a similar process being applied to second jaw 12 b.FIG. 17 illustrates mouse-clicking 170 on point 114 f of firstconstellation of points 114 and mouse-clicking 170 on point 164 c ofthird constellation of points 164. In response to such mouse-clicking,computer 106 determines that points 114 f and 164 c represent the samepoint (feature 42 c) on second jaw 12 b.

FIG. 18 illustrates mouse-clicking 170 on point 114 e of firstconstellation of points 114 and mouse-clicking 170 on point 164 b ofthird constellation of points 164. In response to such mouse-clicking,computer 106 determines that points 114 e and 164 b represent the samepoint (feature 42 b) on second jaw 12 b. Likewise, similarmouse-clicking on point 114 d of first constellation of points 114 andmouse-clicking 170 on point 164 a of third constellation of points 164is interpreted as meaning that points 114 d and 164 a represent the samepoint (feature 42 a) on second jaw 12 b.

The mouse-clicking method, as just described with reference to FIGS.15-18, ties the second scan representation of the first jaw 158 (e.g.,upper jaw 12 a) to the first scan representation of the first jaw 110(e.g., upper jaw 12 a). Such mouse-clicking also ties the second scanrepresentation of the second jaw 160 (e.g., lower jaw 12 b) to the firstscan representation of the second jaw 112 (e.g., lower jaw 12 b).

Next, as shown in FIG. 19, arrows 166 represent shifting the secondconstellation of points 162 and the third constellation of points 164relative to each other such that both the second constellation of points162 and the third constellation of points 164 of the compositeconstellation of points 174 substantially coincide with the firstconstellation of points 114. Such shifting creates digital jaw model116, as shown in FIG. 20, arrow 176 shows how well point 162 c of secondconstellation of points 162 aligns with point 114 c of firstconstellation of points 114. Arrow 178 shows how well point 164 c ofthird constellation of points 164 aligns with point 114 f of firstconstellation of points 114. Consequently, second scan representation ofthe first jaw 158 and second scan representation of the second jaw 160,of digital jaw model 116, are positioned in proper bite registration inaccordance with the bite registration recorded in first scan result 98.

Once digital jaw model 116 is configured in its proper biteregistration, first scan result 98 can be set aside, and dentalpractitioner 168 can now focus on digital jaw model 116, as shown inFIGS. 23 and 24). To help analyze jaws 12 in the treatment of patient10, dental practitioner 168 can view digital jaw model 116 fromdifferent angles, as known software (e.g., exocad, 3shape, dental wings,Dentsply Sirona, etc.) enables computer 106 to rotate digital jaw model116 in virtual 3D space. Such 3D rotation is represented by arrows 180in FIG. 24.

In the example illustrated in FIGS. 21 and 22, dental practitioner 168fits a virtual crown 182 (crown 24) and a virtual new set of dentures184 (dentures 18) to digital jaw model 116. Arrows 186 of FIG. 23represents adding a virtual dental appliance (e.g., crown 24, dentures18, etc.) to digital jaw model 116. FIG. 24 shows the expectedappearance and fit of crown 24 and dentures 18. If the appearance andfit are acceptable, dental practitioner 168 can 3D print, machine orotherwise create an actual physical crown 24 and dentures 18 that matchthe proposed virtual ones.

Although fiducial markers 28 can be of any suitable shape and design,FIGS. 25-27 show three examples. In FIG. 25, marker body 36 is generallyspherical and is overmolded directly onto an integral extension 188 ofscrew 38. The slenderness of extension 188 minimizes radiographicinterference with marker body 36.

In FIG. 26, marker body 36 is overmolded onto a pin 190 that is sized tofit within a blind hole 192 in screw 38. This allows marker body 36 tobe attached to screw 38 for scanning and molding purposes and otherwiseremoved for the comfort of patient 10. In some examples, pin 190 has ashoulder 194 that ensures repeatable positioning of marker body 36relative to screw 38. In some examples, pin 190 is tapered for tightlysecuring pin 190 to screw 38 and for establishing a repeatable stopposition of pin 190 within a similarly tapered version of hole 192.Arrows 196 represent selectively attaching marker body 36 to screw 38and separating marker body 36 from screw 38.

In FIG. 27, a spherical dimple 198 in head 40 of screw 38 provides asuitable surface to which a glue 200 can adhesively bond marker body 36to head 40. A breakable adhesive bond provides a means for selectivelyattaching 202 marker body 36 to screw 38 and separating 204 marker body36 from screw 38.

Here are some additional points worth noting. In FIGS. 14 and 15, marks206 schematically represent the optional second set 58 of three fiducialmarkers 28 d, 28 e and 28 f Thus, arrows 146 and 148 of FIG. 14 alsorepresents creating third scan result 126 by not only scanning at leastone of the second jaw 12 b and physical model 136 of second jaw 12 b butby also scanning at least one of second set 58 of three fiducial markers28 d, 28 e and 28 f attached to second jaw 12 b and physical model 136with an indication (visual image) of the three fiducial markers 28 d, 28e and 28 f thereon.

In FIG. 10, blocks 208 represent converting first scan result 98 to adigital format substantially equal in format to that of second scanresult 124 and third scan result 126. In some examples, the fileconverting step of block 208 is accomplished through dental treatmentplanning software executed by computer 106. As mentioned earlier, someexamples of such software include exocad, 3shape, dental wings, andDentsply Sirona. Some example file types include various versions ofopen mesh data, point cloud data, and DentalCAD HTML scenes. Somespecific example file format extensions include .stl, .obj, .ply, .off,.eoff, .xyz, .xyznb.

Arrow 96 of FIG. 10 illustrates creating first scan result 98 byconcurrently scanning 100 first jaw 12 a and second jaw 12 b of patient10. FIG. 14 illustrates creating second scan result 124 by scanning(arrows 138 and 142) at least one of first jaw 12 a and physical model134 of first jaw 12 a, wherein creating first scan result 98 isaccomplished using first scanning machine 102, creating second scanresult 124 is accomplished using second scanning machine 144, and firstscanning machine 102 and second scanning machine 144 are two differentmachines. FIG. 14 also illustrates creating third scan result 126 byscanning (arrows 146 and 148) at least one of second jaw 12 b andphysical model 136 of second jaw 12 b.

Computer 106 in FIG. 14 illustrates displaying first scan result 98including first scanned representation of the first jaw 110 (upper jaw12 a) and first scanned representation of the second jaw 112 (lower jaw12 b) in a first positional relationship relative to each other (e.g.,jaws 12 in a predetermined proper bite registration). Computer 106 inFIG. 14 illustrates displaying second scan result 124 including secondscanned representation of the first jaw 158. Computer 106 in FIG. 14illustrates displaying third scan result 126 including second scannedrepresentation of the second jaw 160 in a second positional relationship(e.g., jaws 12 a and 12 b widely spaced apart) relative to secondscanned representation of the first jaw 158.

Arrows 166 of FIG. 19 illustrates shifting second scanned representationof the first jaw 158 relative to second scanned representation of thesecond jaw 160 such that the second positional relationship of secondscanned representation of the first jaw 158 relative to the secondscanned representation of the second jaw 160 is substantially equal to(as indicated by arrows 176 and 178 of FIG. 20) the first positionalrelationship of the first scanned representation of the first jaw 110relative to the first scanned representation of the second jaw 112.

Arrow 118 of FIG. 11 illustrates removing at least one of a tooth and adental appliance (e.g., dentures 14) from patient 10 after creatingfirst scan result 98 but before creating second scan result 124.Otherwise, failing to remove such items would interfere with second scanresult 124 and/or third scan result 126 and thus interfere with planningof the patient's treatment.

FIGS. 28-48 illustrate examples that can be used in addition or asalternatives to the examples already described and illustrated in FIGS.1-27. FIGS. 28-37 show a method for analyzing a scan result 210 (e.g.,scan result 98, 124, and/or 126) of fiducial marker 28 attached to jaw12 of patient 1, wherein the method involves the use of computer 106 anda user (e.g., dental practitioner 168) providing a user input 212 (e.g.,mouse clicking 170, keyboard entry, etc.).

In the example of FIGS. 28-37, the method involves computer 106executing digital image analytics 214 (FIG. 37) to accurately identify alocation or center point of a fiducial marker 28 that might appearblurring in the scan image due to a scanning problem known as “scatter.”The term, “digital image analytics” refers to an algorithm executed by acomputer for making a pixel-by-pixel evaluation of a digital image. Insome but not all examples, digital image analytics does a pixel-to-pixelcomparison of two digital images. Such a comparison can be used by thecomputer for iteratively adjusting the position, orientation and/or sizeof one image relative to the other to minimize the differences betweenthe two.

FIG. 28 illustrates displaying, via computer 106, a first perspective ofscan result 210 including a scan representation 216 (e.g. scanrepresentations 110, 112, 158 and 160) of fiducial marker 28. FIG. 29illustrates displaying, via the computer 106, a second perspective ofscan result 210 including scan representation 216 of fiducial marker 28.In the illustrated example, fiducial marker 28 appears blurry due toscatter and/or limited scanning accuracy.

FIGS. 28 and 29 illustrate identifying on scan result 210, via userinput 212, a general location 218 of fiducial marker 28 as viewed fromthe first and second perspectives, FIGS. 28 and 29 respectively.

Arrows 220 and 222 of FIGS. 30 and 31, respectively, represent assigninga geometric feature 224 (e.g., a circle, a sphere, a predefined keypoint 226 such as a center point, etc.) to scan representation 216 offiducial marker 28 in the general location 218 identified by user input212, wherein the geometric feature 224 includes predefined key point226. In some examples, user 168 provides computer 106 with a user inputvia keyboard identifying marker 28 by size (e.g., diameter) or bypart/model number.

Arrows 228 and 230 of FIGS. 32 and 33 illustrate aligning, via computer106 executing digital image analytics, the geometric feature 224 to thescan representation of fiducial marker 28.

FIGS. 34 and 35 show the results of assigning the predefined key point226 to the general location 218 of fiducial marker 28, whereby thepredefined key point 226 provides a more precise location of fiducialmarker 28. In the future, then, whenever user 168 mouse-clicks anywherewithin general location 218, computer 106 assumes the user 168 is reallytrying to more precisely select the predefined key point 226 nowassigned to fiducial marker 28.

In the example shown in FIGS. 36 and 37, scan results are iterativelyadjusted in dimensions of scale (size), orthogonal position and angularorientation till the two scan results (e.g., scans 110 and 158, scans112 and 160, etc.) most closely match by those dimensions. FIG. 36 showsan X-axis 232, a Y-axis 234, a Z-axis 236, a pitch 238 about X-axis 232,a roll 240 about Z-axis 236, and a yaw 242 about Y-axis 234. Arrows 244,246 and 248 represent adjusting along X-axis 232, Y-axis 234, and Z-axis236, respectively. Arrows 250 represent adjustments in size or scale.FIG. 37 illustrates method steps 214 performed by image analyticsoftware executed by computer 106.

In some examples, user 168 provides computer 106 with limits as to howfar computer 106 can scale and shift an image. In some examples,computer 106 provides an error message if computer 106 determines thatan “optimized” adjustment occurs at or beyond such a user-specifiedlimit. In some examples, user 168 does initial visual adjustments to getit in the “ballpark,” and computer 168 later applies digital imageanalytics for final, more precise adjustments. In some examples, themethod illustrated in FIG. 37 can be used with or without fiducialmarkers 28.

FIGS. 38-43 illustrate another example fiducial marker system and methodfor analyzing jaw 12. This example involves using a rubbery moldingmaterial 128 and a casting material 252 (e.g., plaster, cement, epoxy,ceramic, etc.) for creating a cast model 254 (e.g., model 134 or 136).

Referring to FIGS. 38-43 and other previously described figures, arrow48 (FIG. 4) represents attaching fiducial marker 28 to jaw 12, whereinfiducial marker 28 comprises marker body 36 attached to screw 38. Arrow100 of FIG. 10 represents scanning jaw 12 and fiducial marker 28attached thereto. Arrow 256 of FIG. 38 represents removing marker body36 from screw 38. Arrow 258 of FIG. 38 represents attaching a holder 260to screw 38, wherein holder 260 has a first end 262 and a second end264. Holder 260 can be of any desired shape and design but is preferablylarger than marker body 36, so holder 260 can be securely embedded inmolding material 128.

Arrows 266 of FIG. 39 represents applying molding material 128 to jaw 12and to the holder's second end 264 while the holder's first end 262 isstill attached to screw 38. Clock 268 represents allowing moldingmaterial 128 to set while on jaw 12, thereby creating a rubbery mold(e.g., mold 130 or 132) that defines a mold cavity 270. Arrows 266 andclock 268 also represent encasing the holder's second end 264 withinmolding material 128 while allowing molding material 128 to set.

Arrow 272 of FIG. 39 represents separating the holder's first end 262from screw 38 by removing molding material 128 and holder 260 from jaw12 while the holder's second end 264 remains encased within moldingmaterial 128. FIG. 40 shows the resulting mold (e.g., mold 130 or 132)with the holder's second end 264 is encased therein.

Arrows 274 of FIG. 41 represent attaching an anchor 276 to the holder'sfirst end 262 while the holder's second end 264 remains encased withinmolding material 128. The term, “anchor” refers to any structure thatcan be embedded within casting material 252 and provide some means forwhich something else can be attached thereto. Some examples of anchor276 include screw 38 and any other conceivable member 278.

Arrow 280 of FIG. 42 represents filling mold cavity 270 with castingmaterial 252 and thereby encasing anchor 276 within casting material 252while filling mold cavity 270 with casting material 252. Clock 282 ofFIG. 42 represents allowing casting material 252 to set. Arrow 284 ofFIG. 42 represents removing casting material 252 from within the moldcavity 270 while anchor 276 remains encased within casting material 252.Arrow 286 of

FIG. 42 represents removing holder 260 from anchor 276 by removing themold (e.g., mold 130 or 132) from the hardened casting material 252.

Arrows 288 of FIG. 43 represent attaching a piece 290 to anchor 276where the holder's first end 262 was previously attached to anchor 276.Examples of piece 290 include marker body 36 (or some resemblancethereof), holder 260 (or some resemblance thereof), and any otherconceivable tool or fixture 292 that might prove useful in variousdental treatments.

Some examples of fiducial marker 28, as shown in FIG. 44, head 40 has ahead outer perimeter 294 with a plurality of faces 296. The plurality offaces 296 face radially outward from longitudinal axis 34 to bedrivingly engaged by a suitable tool (e.g., a wrench). In some examples,screw 38 and head 40 are made of a monolithic piece of a first material(e.g., a metal). Example geometries of head 40 include a six-sided prism(hexagonal cross-section), a four-sided prism (square cross-section), astar prism (e.g., Torx head), etc.

Still referring to FIG. 44, marker body 36 has a marker outer perimeter298 and is made a second material (e.g., a polymer) distinguishable fromthe first material of screw 38. In some examples, second material ispolymethyl methacrylate (e.g., PMMA or acrylic) impregnated with 10% (byvolume) barium sulfate, so marker body 36 is substantially radiopaque.

In the illustrated example, extension 188 connects marker body 36 tohead 40 of screw 38, such that screw 38, head 40, marker body 36 andextension 188 are coaxially aligned with longitudinal axis 34. Tofacilitate the installation and removal of fiducial marker 28, headouter perimeter 294 extends a first radial distance 300 fromlongitudinal axis 34, marker outer perimeter 298 extends a second radialdistance 302 from longitudinal axis 34, and first radial distance 300 isgreater than second radial distance 302. In some examples, marker body36 is one to three millimeters in diameter for greater positionalaccuracy. In some examples, to minimize certain scanning distortion orscatter, extension 188 extends a third radial distance 304 fromlongitudinal axis 34, wherein third radial distance 304 is less thansecond radial distance 302.

Some examples of fiducial marker 28, as shown in FIGS. 45 and 46, have ahead 306 on screw 38 that are of a monolithic piece of a first material(e.g., a metal) with a socket 308 in head 306. Socket 308 is of a sizeand shape (e.g., square) to matingly engage with and to receiveselectively an extension 310 of marker body 36 or a tool 312 forinstalling or removing screw 38 from jaw 12. FIG. 47 shows tool 312inserted into socket 308, and FIG. 48 shows extension 310 inserted intosocket 308.

In some examples, marker body 36 is made of a second material (apolymer) that is distinguishable from the first material of screw 38,thereby making marker body 36 easier to identify in a scan result. Insome examples, extension 310 includes a slot 314 that enables extension310 to resiliently flex and snuggly fit in socket 308. In some examples,extension 310 includes a protrusion 316 that helps secure extension 310to head 306 of screw 38.

To minimize scatter distortion in scan results, some examples offiducial marker 28 have extension 188 (or extension 310) be lessradiopaque than marker body 36. In some examples, extension 188 is madeof a polymeric extension material with virtually no barium sulfate,while marker body 36 is made of a second polymeric material with 10%barium sulfate. In some examples where extension 188 and marker body 36are made of different materials, the two materials (the marker body'spolymer with barium sulfate and the extension's polymer without bariumsulfate) are co-molded as a unitary but nonmonolithic piece. The processof co-molding is also known as overmolding, multi-material injectionmolding, and MMM.

FIGS. 49-69 illustrate various items and methods that, in some examples,can be used as alternatives to the items and methods shown in FIGS.38-43. FIGS. 49 and 50 show another example of fiducial marker 28. Inthis example, marker body 36 is on head 315 of screw 38. A socket 325 inhead 315 enables screwing screw 38 into jaw 12.

FIG. 51 shows what's known as an analog 318. In some examples, analog318 is basically a combination of anchor 276 and marker body 36 (oractually a marker body model 320 of the same size and shape of markerbody 36). Some examples of analog 318 include a pin 322, which will beexplained later with reference to FIGS. 64-69. In some examples, pin 322can be broken off, cut off, ground off, or otherwise removed from markerbody model 320 to create an analog 318′, as shown in FIG. 52.

FIGS. 53-55 show an example holder 324, which is somewhat of asubstitute for holder 260 of FIGS. 38-43. Holder 324 includes areceptacle 326 for receiving selectively marker body 36 or marker bodymodel 320. Holder 324 is of a size and shape to create a snap-in orinterference fit with marker body 36 (FIG. 56) and marker body model 320(FIG. 57). Some examples of holder 324 include an appendage 328 thathelps secure holder 324 in position, as will be explained later withreference to FIGS. 58-63.

FIGS. 58-63 illustrate an alternative to the example shown in FIGS.38-43, wherein FIGS. 58-63 correspond to FIGS. 38-43, respectively. FIG.58 shows fiducial marker 28 screwed into jaw 12. Arrow 258 representsattaching holder 324 to marker body 36.

FIG. 59 shows holder 324 snapped onto or otherwise firmly attached tomarker body 36 while molding material 128 encases holder 324 and much ofjaw 12. The holder's appendage 328 is of a shape that securely anchorsholder 324 to the set molding material 128. In some examples, appendage328 includes multiple holes 330 to enhance the bond between appendage328 and molding material 128. Holder 324 is particularly useful in caseswhere fiducial marker 28 is beyond a reasonable reach of moldingmaterial 128 within jaw 12.

After molding material 128 sets, molding material 128 (impression) isremoved from jaw 12 and separated from fiducial marker 28, while holder324 remains encased within molding material 128, as shown in FIG. 60.Holder 324 has an open end 332 that allows marker body 36 to slidevertically out from within receptacle 326 as molding material 128 isremoved from jaw 12.

FIG. 61 shows marker body model 320 of analog 318′ being inserted intoreceptacle 326 of holder 324. It should be noted, however, that in thisexample, pin 322 is first removed from marker body model 318, as pin 322is not needed for this particular method. As mentioned earlier, in someexamples, marker body model 320 snaps into receptacle 326 to help holdmarker body model 320 in place as casting material 252 is poured intomold cavity 270.

FIG. 62 shows casting material 252 having been poured into cavity 270,and thereby encasing one end 336 of analog 318′. After casting material252 hardens to create cast model 254, molding material 128 is removedalong with the embedded holder 324. FIG. 63 shows the resulting castmodel 254 with the protruding marker body model 320. Marker body model320 attached to cast model 254 can be used as a dimensional referencepoint, used as a tool attachment point, and/or used for carrying outvarious dental procedures.

FIGS. 64-69 illustrate another alternative to the example shown in FIGS.38-43, wherein FIGS. 64-69 correspond to FIGS. 38-43, respectively. Themethod shown in FIGS. 64-69 can be used when fiducial marker 28 is wellwithin the reach of molding material 128. In this example, FIG. 64 showsfiducial marker 28 screwed into jaw 12.

FIG. 65 shows molding material 128 encasing marker body 36 and asignificant portion of jaw 12. After molding material 128 sets, moldingmaterial 128 is removed from jaw 12 and separated from fiducial marker28, as shown in FIG. 66. The removal of marker body 36 from moldingmaterial 128 leaves a marker cavity 334 in the set molding material 128.Marker cavity 334 provides an accurate impression of marker body 36.

FIG. 67 shows marker body model 320 of analog 318 being inserted intomarker cavity 334 of molding material 128. Upon pressing marker bodymodel 320 into marker cavity 334, pin 322 pokes into molding body 128,which prevents marker body model 320 from rotating within marker cavity334. Consequently, marker body model 320 is held firmly in place ascasting material 252 is poured into mold cavity 270.

FIG. 68 shows casting material 252 having been poured into mold cavity270, and thereby encasing one end 336 of analog 318. After castingmaterial 252 hardens to create cast model 254, molding material 128 isremoved from cast model 254 and from analog 318 embedded therein. FIG.69 shows the resulting cast model 254 with the protruding marker bodymodel 320 with its pin 322. Arrow 338 represent removing pin 322 frommarker body model 320, as pin 322 has served its purpose and is nolonger needed. Marker body model 320 attached to cast model 254 can nowbe used as a dimensional reference point, used as a tool attachmentpoint, and/or used for carrying out various dental procedures.

FIGS. 70-76 show an example fiducial marker 340 similar to the exampleshown in FIGS. 45-48 but with some improvements. Fiducial marker 340, inthis example, includes a screw 342 (FIGS. 70 and 71) and a marker body344 with an extension 346 (FIGS. 72, 73 and 74).

Screw 342 is elongate to define a longitudinal axis 348 that isperpendicular to a radial direction 350. A head 352 of screw 342 definesa socket 354 for receiving selectively extension 346 of marker body 344or tool 312. In some examples, extension 346 has a substantiallycylindrical outer surface 356, so extension 346 can be easily insertedinto socket 354 in any rotational orientation. The term, “head” simplyrefers to one end of screw 342 and does not necessarily mean that head342 is of a larger diameter than the rest of screw 342. In someexamples, screw 342 and head 352 provide a monolithic piece of a firstmaterial consisting mostly of a metal (e.g., titanium, tungsten,stainless steel, etc.).

In the illustrated example, socket 354 includes a substantiallycylindrical inner surface 356 and a plurality of inward facing facets360. Cylindrical inner surface 356 is substantially concentric withlongitudinal axis 348. Facets 360 are substantially parallel to thescrew's longitudinal axis 348. The term, “inward facing facets” meansthat the facets 360 face into the central cavity of socket 354.

To reduce radiographic scatter and image distortion, marker body 344 ismade of a second material that is less radiopaque than the firstmaterial of screw 342. So, in some examples, the second material is amixture 366 of a polymeric binder 362 and a radiopaque filler material364. In some examples, extension 346 is a seamless integral extension ofmarker body 344, whereby marker body 344 and extension 346 are both madeof the second material.

Some examples of polymeric binder 362 include acrylic, polymethylmethacrylate (PMMA), polycarbonate, polystyrene, high-impact polystyrene(HIPS). Some examples of filler material 364 include metallic material,barium, titanium, bismuth, tungsten, zirconium, and various compoundsthereof. In some examples, filler material 364 includes barium sulfate,which can be finely mixed with polymeric binder 362.

In some examples, the proportions of binder 362 and filler material 364may be important. Too much filler material 364 may create one or moreproblems, such as undesirable scatter in first scan result 98,structural weakness in extension 346, and/or difficulty in plasticinjection molding the material. An insufficient amount of fillermaterial 364 may render marker body 344 so radiographically transparentthat it becomes difficult to distinguish marker body 344 from humantissue. Consequently, in some examples, filler material 364 is more thantwice as dense as polymeric binder 362 and makes up 20% to 70% of themixture's volume to provide mixture 366 with a density of 1.8 to 2.9grams per cubic centimeter, which falls somewhere between the density ofjaw bone and tooth enamel. Particularly favorable results are achievedwhen mixture 366 is mostly polymeric binder 362 by volume (i.e.,polymeric binder 362 contributes at 50% of the mixture's volume).

Socket 354 is of a size and shape to receive selectively tool 312 or themarker body's extension 346. Fiducial maker 340 provides a press-fit inradial direction 350 between the substantially cylindrical outer surface356 of extension 346 and the substantially cylindrical inner surface 358of socket 354 when extension 346 is inserted into socket 354. Tool 312engages the plurality of inward facing facets 360 when tool 312 isinserted into socket 354. Fiducial marker 340 provides a slip-fit inradial direction 350 between tool 312 and socket 354 when tool 312 isinserted into socket 354.

The term, “press-fit” refers to two parts fitting matingly together byvirtue of at least one of the parts being in compression or tensionrather than relying on clearance between the parts. The term, “slip-fit”refers to two parts fitting matingly together by virtue of clearancebetween the parts rather than relying on compression or tension of oneor both of the parts.

To provide socket 354 with both cylindrical surface 358 and inwardfacing facets 360, some examples of screw 342 include both a round hole368 (cylindrical hole) and a square hole 370, which are concentric witheach other. In some examples, round hole 368 serves as a drilled pilothole for facilitating the subsequent broaching of square hole 370.

Here are some additional points worth noting. The term, “computer”refers to computer hardware itself plus software programs runningthereby either locally or remotely. The term, “substantially match”refers to a comparison with differences that have been minimized. Theterms, “first perspective” and “second perspective” refer to directionsin which a virtual 3D object is viewed. For example, a first perspectivecould be a front view along a Z-axis, and a second perspective could bea side view along an X-axis. A top view along a Y-axis is anotherexample perspective. First and second perspectives do not necessarilyhave to be perpendicular to each other.

Although certain example methods, apparatus and articles of manufacturehave been disclosed herein, the scope of coverage of this patent is notlimited thereto. On the contrary, this patent covers all methods,apparatus and articles of manufacture fairly falling within the scope ofthe claims of this patent.

1. A fiducial marker adapted to be screwed into a jawbone, the fiducial marker comprising: a screw being elongate to define a longitudinal axis that is perpendicular to a radial direction, the screw being of a first material; a marker body being of a second material that is less radiopaque than the first material; and an extension extending between the marker body and the screw, the extension being of an extension material that is substantially equal to one of the first material and the second material.
 2. A fiducial marker adapted to be screwed into a jawbone via a tool, the fiducial marker comprising: a screw being elongate to define a longitudinal axis that is perpendicular to a radial direction; a head on the screw, the head defining a socket, the screw and the head being of a monolithic piece of a first material consisting mostly of a metal; a marker body being of a second material that is a mixture of a polymeric binder and a filler material, the filler material being 20% to 70% of the mixture by volume, the filler material being more than twice as dense as the polymeric binder, the mixture having a density of 1.8 to 2.9 grams per cubic centimeter, the second material of the marker body being less radiopaque than the first material of the screw; and an extension extending from the marker body, the socket being of a size and shape to receive selectively the tool and the extension, the tool matingly engaging the socket when the tool is disposed within the socket.
 3. The fiducial marker of claim 2, wherein the extension includes a substantially cylindrical outer surface, the socket includes a substantially cylindrical inner surface that is substantially concentric with the longitudinal axis of the screw, and the socket includes a plurality of inward facing facets that are substantially parallel to the longitudinal axis of the screw.
 4. The fiducial marker of claim 3, wherein the fiducial maker provides a press-fit in the radial direction between the substantially cylindrical outer surface and the substantially cylindrical inner surface when the extension is disposed within the socket, the tool engages the plurality of inward facing facets when the tool is disposed within the socket, and the fiducial marker provides a slip-fit in the radial direction between the tool and the socket when the tool is disposed within the socket.
 5. The fiducial marker of claim 2, wherein the filler material is metallic.
 6. The fiducial marker of claim 2, wherein the filler material includes barium sulfate.
 7. The fiducial marker of claim 2, wherein the extension is a seamless integral extension of the marker body, whereby both the marker body and the extension are of the second material.
 8. A fiducial marker adapted to be screwed into a jawbone via a tool, the fiducial marker comprising: a screw being elongate to define a longitudinal axis that is perpendicular to a radial direction; a head on the screw, the head defining a socket, the screw and the head being of a monolithic piece of a first material consisting mostly of a metal; a substantially cylindrical inner surface within the socket, the substantially cylindrical inner surface being substantially concentric with the longitudinal axis of the screw; a plurality of inward facing facets on the head to define at least some of the socket, the plurality of inward facing facets being substantially parallel to the longitudinal axis of the screw; a marker body being of a second material that is a mixture of a polymeric binder and a filler material, the filler material being 20% to 70% of the mixture by volume, the filler material being more than twice as dense as the polymeric binder, the mixture having a density of 1.8 to 2.9 grams per cubic centimeter, the second material of the marker body being less radiopaque than the first material of the screw; an extension extending from the marker body; and a substantially cylindrical outer surface on the extension, the socket being of a size and shape to receive selectively the tool and the extension, the fiducial maker providing a press-fit in the radial direction between the substantially cylindrical outer surface and the substantially cylindrical inner surface when the extension is disposed within the socket, the tool engaging the plurality of inward facing facets when the tool is disposed within the socket, and the fiducial marker providing a slip-fit in the radial direction between the tool and the socket when the tool is disposed within the socket.
 9. The fiducial marker of claim 8, wherein the filler material is metallic.
 10. The fiducial marker of claim 8, wherein the filler material includes barium sulfate.
 11. The fiducial marker of claim 8, wherein the extension is a seamless integral extension of the marker body, whereby both the marker body and the extension are of the second material. 